Spit flow hydrodesulfurization of petroleum fraction

ABSTRACT

Heavy hydrocarbon oils are desulfurized in a split flow catalytic process in which the upper catalyst bed temperature is at least 875*F. and the lower catalyst bed temperature is below 850*F.

United States Patent 1191 Franz et al.

[451 July 29, 1975 1 SPLIT FLOW HYDRODESULFURIZATION OF PETROLEUM FRACTION [75] Inventors: William F. Franz, Gardiner; Howard V. Hess, Glenham, both of NY.

[73] Assignee: Texaco Inc., New York, NY.

[22] Filed: Dec. 26, 1973 [21] Appl. No.1 427,875

52 11.5. C1 208/210; 208/59 51 1n1.c1 ..Cl0g 23/00 581 Field of Search 208/210, 89,218, 58, 59,

[56] References Cited UNITED STATES PATENTS 2,844,517 7/1958 lnwood 208/210 Primary Examiner-Delbert E. Gantz Assistant ExaminerG. J. Crasanakis Attorney, Agent, or Firm-Thomas H. Whaley; Carl G. Ries; Robert Knox [57] 1 ABSTRACT Heavy hydrocarbon oils are desulfurized in a split flow catalytic process in which the upper catalyst bed temperature is at least 875F. and the lower catalyst bed temperature is below 850F.

10 Claims, No Drawings I SPLIT FLOW HYDRODESULFURIZATION OF PETROLEUMFRACTION 2 This invention relates to the treatment of petroleum oils. More particularly, it is concerned with the production of hydrocarbomoils of reduced sulfur contentfrom heavy hydrocarbon oils'containingtar and asphalt.

these products. To .this end, a crude petroleumv oil isdistill'edto obtain these fractions as distillates and the materials boiling -'above the desired products such as the'heavier gas oils are subjectedtov cracking. and/or hy; drocracking to convert them to lighter products. For ecological reasons, it is now important that these fuels also contain a minimum amount of sulfur-.lf the crude petroleumoil-has been distilled under atmospheric pressure up to a-temperature at which incipient cracking begins, usually. between about 650 =and 750F., there remains in the still a'residue generally referred to as atmospheric residuum containing relatively large amounts of tar and asphalt. This atmospheric, residuum may be further distilled under reduced pressure to pro duceas distillate vacuum gas oils leavinga still residue generally referred to as vacuum residuum. Attempts to convert still residues into more valuable products by means of catalytic processes have not been particularly successful as tar and asphalt tend to settle on the catalyst and over a period of time form a layer of coke which prevents the oil from coming into. contact with the" catalyst therebymeducingthe catalyst activity. P

Because of the many-legalrequirements restricting the amount of sulfur present'in. fuels, it hasbecome necessary to treat moreand more hydrocarbon oils for the removal of sulfur. Conventionally this is ,done by contacting the hydrocarbon oil at elevated temperature and pressure in the presenceof hydrogen with-a desulfurization catalyst whereby the sulfur present in the oil is converted to hydrogen sulfide and may be separated with relative ease from the hydrogen which can then be recycled to the reaction zone. Because of the greater volumes of oilswhich'must be treated the; amount of hydrogen required has greatly increased; and it has been necessary to augment refinery facilities with hydrogenproducing plants. Hydrogen consumption will vary depending on the charge stock and the amount of desulfurization required but generally it will amount to between 400 "and 500 standard cubic feet per barrel of oil.

It would therefore be a great saving if the amount of hyproducts. Our invention contemplatesaprocess which comprises charging the heavy hydrocarbon" oil together with hydrogen at elevated temperature and pressure into a bed'of catalyst particles. Thatportion of the petroleum oil'wh'ich is still liquid at reactionconditions passes downwardlythrough the catalyst bed and'is met by an -upwardly flowingstrcam'of hydrogen..The' hydrot 1H; i

'gen passes upwardly through the catalyst bed while contacting the. oil, and catalyst and becomes rhixedwith vaporous hydrocarbon materials fori'ned either by'ithe .catalyticreaction which takes place as the l iquid oil flows downwardly through the bed or vaporous hydro; carbons which have been formed during'the heating .of the oil ,feed. The mixture of hydrogen and yapo rous hydrocarbons is then passed to a separate catalytic 'ione wherethe vaporous materials are subjected to des ulfurization conditions. According to apreferred embo diment of our invention, the oil optionally with portion.

ofthe hydrogen is introduced into a fixed bed of particulate catalyst to permitthe liquid portion of the oil to flowdownwardly through the catalyst bed at a temper ature below 850F. and the vaporous material formed during the heating of the charge oiland/or produced by the catalytic reaction during the downward flow of the liquid oil through the catalyst bed is passed in vapor phase withhydrogen introduced at the bottom of the bed into a. catalyst bed maintainedat a temperature above 875F. By following theprocedure of our inven tion good yields of'oils of reduced sulfur content and lower boiling range are obtained with lower hydrogen consumption.

The oil used as charge to. the process of our invention is a heavy oil ordinarily ,having an initial boiling point between about 550 and 750%". with atlleast percent boiling above 650 F. and preferably at least about percent boiling above 650F. Typically, it has a-con radson Carbon Residue of at least 1 percent weight and usually at least 5 percent by weight. Examplesof such chargestocks are atmospheric residua, vacuum residua and heayy distillates such as vacuum gas oils obtainedfrom crude petroleum, shale oil, tar sand, oil and the like. l The hydrogenused inour process need notnecessarilybe pure. Hydrogenhaving a purity of. at easrso per cent and preferably at least;6 5 percent may be used. Suitable sources of hydrogen are catalytic reformeribyproduct hydrogen, electrolytic hydrogen and hydrogen 1 produced by partial oxidation of acarbonaceous or hydrocarbonacepus materialfollowed by shift conversion .and C-O removaL In a preferred embodiment, hydrogen at arateof between 500 and 5000 standard cubic feet perbarrel is introduced into the catalyst bed; with the oil feed and hydrogen is introduced into the b'ottom of the catalyst bed to flow upwardly therethr'ough atia irategbetween 3,000 and 20,000 scfb preferably between 8,000 and 15,000 scfb. I

The catalyst used in ourprocesscomprises a Group VIII. metal and/or compound thereof optionally composited. with a Group VI metalor compound thereof on -.a support comprising a refractory inorganic oxide. The .Group VIII metal is preferably an iron group metal suchas nickel or cobalt or a mixture thereof. Suitable Group-.Vl metals are molybdenum and tungsten. Preferred hydrogenating components are mixtures of the {metal oxides or sulfides such as cobalt oxide and mo},

lybdenum :oxide, nickel sulfide. and tungsten sulfide,

.nickel oxide, cobalt oxide and molybdenuiniox ide.

- Suitable supports for the hydrogenating components of the,catalyst comprise inorganic oxides such as alumina,

alumina stabil zed with a m1nor amount, for example,

silica, magnesia, .titania, beryllia zirconiaand the like and: mixtures thereofa A preferred support comprises a; less than-15 percent silica hasedby weight on the cata- 1 .lyst composite. The catalyst is used as a fixed bed'with 3 catalyst particles'The particles may have spheroidical or cylindrical shapes. In a preferred embodiment the catalyst bed is made up of cylindrical particles having a maximum dimension of between one-half inch and one-sixteenth inch.

The Group V111 metal may be present in an'amount between about 1 and 15 percent by weight preferably between about 1.5 and 10 percent by weight of the catalyst composite. When present, the Group V1 metal may comprise between about 3 and 30 percent preferably between about 5 and 20 percent by weight of the catalyst composite. Particularly suitable catalysts comprise about 2 percent iron group metal such as nickel or cobalt and about 18 percent Group V1 metal such as molybdenum or tungsten. Advantageously the catalyst contains a minor amount of silica e.g.,'less than about percent such as 2-4 weight percent of the catalyst composite.

1n carrying out the process of this invention, the heavy hydrocarbon oil charge stock is introduced into a desulfurization catalyst zone herein defined to include a first catalyst zone in downflow relationship to the downward flow of the heavy hydrocarbon stock and a second catalyst zone above the point of entry of the heavy hydrocarbon charge stock and in upflow relationship to the lower boiling hydrocarbons which proceed from the first catalyst zone into the second catalyst zone. By the use of the term downward flow is meant that the heavy hydrocarbon charge stock proceeds in downflow relationship to the first catalyst 'zone. By the use of the term above in reference to the second catalyst zone is meant only that the second catalyst zone is in upflow relationship to the flow of the hydrogen containing gas and in upflow relationship to the volatile hydrocarbon and any entrained liquid hydrocarbon proceeding from the first catalyst zone into asecond catalyst zone. The word above" is used to define a flow relationship with the first catalyst zone, which relationship provides for the flow of hydrogen, volatile hydrocarbons and entrained lower boiling hydrocarbons from the first catalyst zone in countercurrent relationship with the downward flow of the heavy hydrocarbon charge stock into a second catalyst zone. Thus the second catalyst zone can be located directly in a space dimension above the first catalyst zone such as when the first and second catalyst zones are present in .a single reactor vessel with an intermediate point of entry for the heavy hydrocarbon charge stock. However, this invention contemplates that the second catalyst zone can be present in a separate reactor vessel which is connected to a first reactor by conduit means, although it is preferred in carrying out the process of this invention to use a vertical reactor wherein the first catalyst zone and second catalyst zone are present in the same reactor vessel. Within the first and second catalyst zone is a catalyst which has hydrodesulfurization activity under process conditions of temperature, pressure and space velocity which are utilized during the process. In addition, the catalyst in the first catalyst zone can be either the same or different than the catalyst present in the second catalyst zone.

The heavy hydrocarbon charge stock upon entry to the catalyst zone proceeds downwardly in downflow relationship to the first catalyst 'zone. Hydrogen is in- 6 troduced into the first catalyst zone at or near the lower extremity and, if desired, at intermediate points in said first catalyst zone in countercurrent relationship to the hydrocarbon charge flow through the first catalyst zone and in upflow relationship to the second catalyst zone. Volatile hydrocarbons and the lower boiling entrained hydrocarbons proceed with the hydrogen into the second catalyst zone. The volatile hydrocarbons and the entrained liquids after contact with the catalyst leave the second catalyst zone and are recovered by conventional means such as by cooling of the hydrocarbon vapors and liquid. The hydrogen which proceeds from the second catalyst zone may then be recycled together with fresh make-up hydrogen into the first catalyst. zone. 1n addition. hydrogen optionally can be blended with the heavy hydrocarbon charge stock and introduced at ambient temperature or higher such as temperatures up to desulfurization temperatures into the. catalyst zone.

-'The temperature in the first desulfurizationcatalyst zone may range between about 550 and 850F. prefer: ably between 700 and 850F. The temperature in the second catalyst zone should be at least 875F. but not more than about 1,000F. A preferred temperature range is from 880 to 950F. Pressures in both of the re-.'

action zones may range between about 500 and 5,000 psig, a preferred pressure range being from 1,000 to 2,500 psig. The residue-containing petroleum fraction may be introduced into the catalytic-zone at a space velocityof between about 0.1 and 5 volumes of oil per volume of catalyst per hour based on the total volume of catalyst in both desulfurization zones, apreferred range being from 0.25 to 2 v/v/hr.

By following our novel procedure it is possible to convert heavy oils into products of reduced sulfur content while -in'curring a hydrogen consumption of be tween about 100 and 300 scfb whereas, by following known procedures an equivalent amount of. sulfur reduction would incur a hydrogenfconsumption in excess of400scfb. l

.The following examples are submitted for illustrative purposes only and it should not be construed thatthe invention is limited thereto. I

EXAMPLE 1 g The charge in this example is an atmospheric reduced crude derived from West.Texas-New Mexico The charge is introduced into the catalytic zone in a single reactonvessel at a point where 45 percent of the catalyst is above and percent below the point of introduction. The catalysLin pellet form, contains 3 wt;

percent cobalt oxide and 1'1- wt. erc ent molybdenum oxide supported on alumina. Hydrogen is, introduced with the charge ata rate of 4000 scfb. and .is also i'ntro duced at the bottom of the: lower catalyst bed-atla rate tion off-the catalyst inthelower bed is'3 percent oxide and 13.6 percent imolybdenumoxide on aluminm the charge vfeed'rate is-'0:45 wlw/hrx-Hydrogem'is.intro of 11,000 sc'fbxChar-ge rate is 0.4 l weight of .oll per 5 duced with the. charge at a-rategof8800 scfbandalso.. total weight'of catalyst-perhbur and pressutfiimthe rev at the bott 9 the loweF-calalyst 'bedialia action zoneis 1500 ,psige-Dataon thefrun aretabulate'd" 13.000 scfb. Experimental data appe fi Upper 950 950 3 Temp.F-l i 8-25 325 i y Lower 800 800. 1 Time on Stream-Hrs. v 634 814 1B?400 1 ."FlaCtlOn Wl. .%'f 15.9 20.7 A=Pl Gravity 53.4 53.7 'Sulfur-wt. 7: y HLC'. Paraffins w 1 Type {'Naphtheri'es Anal. Aromatics 400500F'. Fraction-wt. 7( 7.1 7.2 API Gravity 32.2 34.5

Sulfur-wt. 7c 0.023 Smoke Point-mm 9 l1 Aniline Point F. 64.7 75.1 500 6500": Fraction -wt. 7 g 7.5 10.4 APlGravity 2 8.6 28.0 23.0 24.9 Sulfufiwtil i 0.016 v 3 0.031 0.057 650-850F. Fraction-wtf/r, -'1.1.3 {13,1 13.4 16.8

API Gravity 23.2 23.6 4 22.7 g I Sulfur-wt. "/1 011:1 0.20 0.33 850-1000F. Fraction-wt. '71 7.1 1118 i .15.6 v 10.5.

API Gravity 21.1 22.3 22.0 20.7 Sulfur-wt. 72 0.26 0.43 0.62 0.6 I000F. Residuum-wt/Z 23.4 23.0 24.5 22.0 APl Gravity 14.5 11.7 10.3 9.7 Sulfur-wt. 71 0.90 1.56 1.7 1.8 H Consumption SCF/BBL 200 200 210 240 below. The temperature designation mid is the tem- These examples show that as the upper section temperature at the point of introduction of the feed and 35 peratures were increased, the measured hydrogen conupper and lower the average temperature of the respective desulfurization catalyst beds.

sumption decreased from 430-450 SCF/bbl. at the lower temperatures to 220 SCF/bbl. at the 900F.

TABLE 11 Period A B C D Upper 825 875 900 950 Temp. F. Mid. 800 800 825 825 Lower 800 800 800 800 Time on Stream-Hrs. l 12 220 286 508 1BP-400F. Fl'LlCliOl'l-WL'Z 7.5 13.1 16.6 14.8 API Gravity 51.1 48.7 50.0 47.7 Sulfur-wt. 0.002 0.001 1 0.007 0.002 H.C. Paraffins 44.0 44.6 44.6 48.2 Type [Naphthenes 34.4 28.0 29.7 18.9 Anal. Aromatics 21.5 27.5 28.8 32.9 400-500F. Fraction-W071 7.5 l 1.2 l 1.8 7.3 API Gravity 39.2 36.7 37.1 30.5 Sulfur-wt. '7: 0.007 0.008 0.011 0.013 Smoke Point mm l3 13 13 l l Aniline Point F. 113.7 116.7 107.6 55.8 500-650F. Fraction-wt. '1 15.2 6.9 9.5 4.4 API gravity 32.6 32.0 30.5 20.5 Sulfur-wt. 71 0.039 0.045 0.071 0.085 650-850F. Fraction-wt. 7: 20.8 20.8 17.7 7.7 API Gravity 28.4 27.4 24.6 19.7 Sulfur-wt. 71 0.38 0.36 0.68 0.59 850-1000F. Fraction-wt. '4 20.5 13.5 18.3 API Gravity 22.2 20.7 22.0 Sulfur-wt. "/1 1.( 1.06 0.99 1000F. Rcsiduum-wt. 71 28.0 48.0 30.8 33.2 API Gravity 7.8 14.8 9.4 9.8 Sulfur-wt. "/1 2.56 1.76 2.34 2.26 H Consumption-SCF/BBL. 430 450 220 150 includes XSU-HKKPF Fraction EXAMPLE 11 vuppcr section temperature, and to 150 SCF/bbl. at the 950F. upper temperature. Sulfur contents. and other properties, of the fractions boiling above 500F. did not greatly change as the overhead temperature was raised but the lighter naphtha and kerosene fraction did show a significant response. Aromatic content of the naphtha is 11) percent cobaltyoxideoniialuminaiand the.composi-i 1 increased from 2L5 percent at the, lowest overhead section temperature to 32.9 at the 95F. temperature.

Obviously, various modifications of theinvention as hereinbefore set forth maybe made without departing from-the spirit and scope thereof, and therefore, only such limitations should be made as are indicated in the appended claims.

We claim: I

1. A process for the conversion of a residuecontaining petroleum fraction into lighter products of reduced sulfur content in which the hydrogen consumption is between 100 and300 scfb which comprises introducing said petroleum fraction through a point of entry into a desulfurization reactor comprising a first hydrodesulfurization catalyst zone below and a second hydrodesulfurization catalyst zone above said point of entry to flow downwardly through said first catalyst zone in countercurrent flow relationship to hydrogen passing upwardly through said first catalytic zone, pass- 2. The process, of claim lin which the .=te.mpcrature of the first catalyst zone is between 700 and 850F.

3. The process of claim in which said hydrogenvconsumption-is'betweeh I50 and 220 scfbhg 4. The proces s of claim l in which hydrogen is introduced into said desulfur'iza tion reactorwi th' said residuecontaining petroleum fractional-.21 rate between 500 and 5,000 scfi).

5. The process of claim I in which said hydrogen is introduced into said first catalytic zone at a rate of at least 3,000 scfb.

6. The process of claim 5 in which hydrogen is introduced into said desulfurization reactor with said residu ef containing petroleum fraction at a rate between 500 and 5000 scfb.

7. 'The process of claim 5 in which said hydrogen is introduced at a rate between 8,000 and 15,000 scfb.

8. The process of claim 1 in which said residuec'ontaining petroleum fraction is a vacuum gas oil.

9. The process of claim I in which said residuecontaining petroleum fraction is an atmospheric resid- 10. The process of claim 1 in which said residuecontaining petroleum fraction is a vacuum residuum. 

1. A PROCESS FOR THE CONVERSION OF A RESIDUE-CONTAINING PETROLEUM FRACTION INTO LIGHTER PRODUCTS OF REDUCED SULFUR CONTENT IN WHICH THE HYDROGEN CONSUMPTION IS BETWEEN 100 AND 300 SCFB WHICH COMPRISES INTRODUCING SAID PETROLEUM FRACTION THROUGH A POINT OF ENTRY INTO A DESULFURIZATION REACTOR COMPRISING A FIRST HYDRODESULFURIZATION CATALYST ZONE BELOW AND A SECOND HYDRODESULFURIZATION CATALYST ZONE ABOVE SAID POINT OF ENTRY TO FLOW DOWNWARDLY THROUGH SAID FIRST CATALYST ZONE IN COUNTERCURRENT FLOW RELATIONSHIP TO HYDROGEN PASSING UPWARDLY THROUGH SAID FIRST CATALYTIC ZONE, PASSING SAID HYDROGEN UPWARDLY WITH VOLATILE HYDROCARBONS AND ENTRAINED LIQUIDS INTO AND THROUGH SAID SECOND CATALYST ZONE AND RECOVERING SAID PRODUCTS OF REDUCED SULFUR CONTENT FROM THE REACTION EFFLUENT OF SAAID FIRST AND SECOND CATALYST ZONES, THE TEMPERATURE IN SAID FIRST CATALYST ZONE BEING MAINTAINED BETWEEN 550* AND 850*F. AND THE TEMPERATURE IN SAID SECOND CATALYST ZONE BEING MAINTAINED BETWEEN 875* AND 1000*F.
 2. The process of claim 1 in which the temperature of the first catalyst zone is between 700* and 850*F.
 3. The process of claim 1 in which said hydrogen consumption is between 150 and 220 scfb.
 4. The process of claim 1 in which hydrogen is introduced into said desulfurization reactor with said residue-containing petroleum fraction at a rate between 500 and 5,000 scfb.
 5. The process of claim 1 in which said hydrogen is introduced into said first catalytic zone at a rate of at least 3,000 scfb.
 6. The process of claim 5 in which hydrogen is introduced into said desulfurization reactor with said residue-containing petroleum fraction at a rate between 500 and 5000 scfb.
 7. The process of claim 5 in which said hydrogen is introduced at a rate between 8,000 and 15,000 scfb.
 8. The process of claim 1 in which said residue-containing petroleum fraction is a vacuum gas oil.
 9. The process of claim 1 in which said residue-containing petroleum fraction is an atmospheric residuum.
 10. The process of claim 1 in which said residue-containing petroleum fraction is a vacuum residuum. 